When my son was about 9 months old, I flew with him from Chicago to Los Angeles. He had flown several times before, but I was by myself with him this time. Like the previous mom said, try to relax as they will pick up on that. At the time, from Midway, I was able to take his milk through only. Not juice. I did have jars of baby food in his diaper bag and they counted as liquids so they had to be in the plastic bag also. I did have to nurse him once on a plane and I just had my own blanket to cover up some. The airline blankets are too heavy and hot, and probably dirty so I just used my own.
Also, if you fly Southwest and can pick your own seats, just try to sit with others with kids. Sometimes they entertain themselves! We always take a portable DVD player and that has worked great once when we were stuck at the gate on the plane for 2 hours!!
I always buy (or borrow) a small amount of new toys that he's never seen before and gradually get those out if he fusses on the plane. I take snacks, too. We've always had really good luck with Southwest and them helping with kids. Once the flight attendant even walked him up and down the aisle for me to keep him entertained for a few minutes.
I know you are nervous, but I'm sure it will be fine. Most people understand in general if a baby fusses and if you are trying to pacify them, that's all you can do. When I fly with my son, and am nervous about the stress of traveling on a plane, I just tell myself it would be much worse traveling in a car with him for 15 hours to Boston:-)
Your baby might even sleep on the way. I've been lucky that way a few times.
Enjoy your trip--it sounds like you are one busy gal!!